The present invention relates to an improved sheave for use in applications, such as in a winch or ratchet, wherein a rope is pulled under tension by either manual or power-driven rotational forces applied to the sheave. This invention relates to pulleys for tightening and tensioning ropes or cords having a ratchet mechanism to permit retaining the same under tension, and more particularly, to such a mechanism which employs the improved sheave to secure a cord or rope which is reeved therein.
Various ratcheting mechanisms have been heretofore used to tighten belts for such applications as tie down straps for securing a load on a vehicle, for boat mooring or anchor systems, tree seats or climbing aids, or other applications wherein it is desirable to be able to tighten a strap which subsequently can easily be released.
Efforts have also heretofore been made to develop sheaves which enable applications of tensile forces to single loops of ropes, cords or cables. In order to ensure adequate gripping of the rope, it has been felt necessary to utilize pointed teeth for this purpose. See for example, British Patent No. 1,233,174 or U.S. Pat. No. 4,151,980, issued May 1, 1979 to Burton et al. The sharp teeth utilized, however, tend to rapidly fray a rope or cord, greatly reducing the service life of the rope or cord due to the rapid destruction thereof. A need has thus existed for improved sheaves and ratchet pulleys employing the same, which would have improved effectiveness in pulling a rope while avoiding shortening the service life thereof.